[The occurrence and distribution of maedi-visna virus infection in lower Austrian sheep breeding establishments]. / Zum Vorkommen und zur Ausbreitung der Maedi-Visna-Virusinfektion in niederösterreichischen Schafzuchtbetrieben.

In a period of one year blood samples of 374 sheep of Lower Austrian flocks were examined in intervals of two months for antibodies against Maedi-Visna (MV). Further on specific attention was paid to the prevalence of MV-infection in the flocks. The antibody-titers were determined by means of agar gel-immunodiffusion test. In 5 (23.8%) of 21 flocks 45 (12.0%) of the sheep were seropositive. Seroprevalence varied within the examined breeds: 19 (27.1%) of 70 Karakul-sheep, 18 (28.1%) of 64 East-Friesian milk-sheep, 7 (9.4%) of 74 Merino sheep and 1 (0.9%) of 111 mountain sheep. None of 55 black-headed sheep showed MV seropositive reaction. Clinical symptoms of Maedi-disease were especially observed in milk-sheep and for the first time in Austria in Karakul-sheep. Unfavorable housing conditions (insufficient room, bad climatic conditions), breed specific behavior patterns (crowding of Karakul-sheep) and a high prevalence of MV infections promote a high incidence the disease.

[Serological studies of antibodies against maedi-visna virus in sheep in Austria]. / Serologische Untersuchung auf Antikörper gegen das Maedi/Visna-Virus bei Schafen in Osterreich.

883 sheep from 68 flocks were tested for the prevalence of antibodies against Maedi/Visna-(M/V)virus. As serological method the Agar Gel Immunodiffusion Test (AGID) was performed, 9.5% of the blood samples were positive against M/V, 1.7% showed questionable results. The highest incidence of serum-antibodies showed the Texel (47.7%) and Milk sheep (26.1%). No antibody titers were found in Mountain and Suffolk sheep. Merino sheep had antibody titers against M/V in 2.6% and Mountain sheep crossbreeds in 1.7%.

[Results of a serological study of the natural spread of maedi-visna virus infection in a sheep herd during an observation period of 30 months]. / Ergebnisse einer serologischen Studie über die natürliche Ausbreitung der Maedi-Visna-Virusinfektion in einer Schafherde während eines Beobachtungszeitraumes von 30 Monaten.

In a sheep population consisting of animals of different breeds the epidemiologic development of the Maedi-Visna-infection was evaluated by means of monthly Immune Diffusion Test (ID) for a period of 30 months. At the beginning the herd consisted of eight animals, where four of them showed clinical symptoms indicative for a MV-infection with positive serological results. The other 4 animals were negative. The herd increased in number by including the offspring and buying in other animals. During the time of 30 months only in one animal a seroconversion could be observed. In nine of 13 lambs borne of seropositive mothers colostral antibodies could be observed. By testing the colostrum of MV-seropositive mothers 6 of 7 animals showed precipitating antibodies. Positive sera showed average titers of 1:2 till 1:64, the highest titer was 1:512. On the postmortal examination of five serological positive animals which were killed because of dominant clinical symptoms, three of them showed MV-lesions partly superinfected with bacteria. In one sheep the diagnosis was pasteurellosis. On a further animal the clinical picture and the histologic results were indicative for the Visna-form of the disease.